Skip to main content

Full text of "Use of sprays to control grasshoppers in fall-seeded wheat in western Kansas"

See other formats


TATE PLANT BOARD 



November 1953 E-868 



United States Department of Agriculture 

Agricultural Research Administration 

Bureau of Entomology and Plant Quarantine 



THE USE OF SPRAYS TO CONTROL GRASSHOPPERS 
IN FALL-SEEDED WHEAT IN WESTERN KANSASi/ 

By R. L. Shotwell 
Division of Cereal and Forage Insect Investigations 



In western Kansas the main grasshopper problem has been the pro- 
tection of newly sprouted fall-seeded wheat from marginal damage by 
the second generation of Melanoplus mexicanus mexicanus (Sauss.). 
The popular method of control has been to spread poisoned bran-sawdust 
bait along the margins of the winter wheat as soon as it sprouts and as 
many times thereafter as is necessary. This control method has 
become a regular fall farm practice and. so routine that some farmers 
have spread bait along wheat margins where no grasshopper infesta- 
tions occurred. 

There are two important reasons why a different control method 
should be developed to take the place of the fall baiting: (1) Bait 
materials are becoming more costly and difficult to obtain, and (2) 
although baiting may offer some protection to the current fall-seeded 
wheat, it does not reduce the general infestation appreciably. Only a 
small part of the infestation is reached in the marginal baiting. 

Problem of the Two Generations 

The situation in western Kansas is of special interest because of 
the two generations of mexicanus . The first generation develops in the 
spring and early summer, when the winter-wheat crop is too far advanced 
to be threatened by any but severe infestations, and the average farmer 
gives the matter little concern. Interest in grasshopper control is not 
aroused until the second generation develops in the late summer and 
fall as a direct threat to the new winter-wheat crop. 

The first generation hatches in the margins and stubble fields during 
April and May, and the grasshoppers reach the adult stage early in June. 
The hatching periods at Tribune, Kans., and also, for comparison, at 



l/ This work was conducted in cooperation with the Bureau's 
Grasshopper Control Project. 






*rn in f. atch 2 to 3 

i and there is no second generation. 

irves, thi ier season an«i 

• for the dif: t*s between the two p! 

sas rr. the eggs 

:. At least it hatch afU 

»f this h 10 days after they are d< 

littli se. Some of ther -.ever, develop to 

August 1 and then remain quiescent until the foK 
s shown in figure 1, most of the eggs of the second genei 
e S< ; •• tnber l . 

hal period of the second generation continues into Octol 
but adults may appear any time after the first week in September, 
is d riod that nymphs hatching adjacent to the fall-seeded 

wheat feed on the margins as the wheat sprouts and develops. The 
degree of damage ds on the numbers of grasshoppers and the 

stage of plant developme: t. Ten grasshoppers per square yard will 
destroy 2 to 3 rods of margins, but a field in which the plants are past 
the 3-leaf stage can be grazed by infestations up to this number without 
h damage. After all, these winter-wheat fields are used for the 

grazing of cattle. 
Adults of the second generation do not begin oviposition until about 
O I :<>. Weather conditions at this time will .•. :':'• I the number of 

eggs deposited and the infestation developing the folio In 

. 32 j • of the egg pods found in the fall egg s of so 

western Kansas wc -.d genera" The heavy egg 

itions red in South Dakota and Nebraska in 19 

atti I that fall and 

which had ample fa\ i Hon in Octobt •■ 

ber. This all in: 

i hus th< e 

In m os I 

until . .'. 

• '-','■• 
rncxu anus , he. 
fixed, and In western 

tch and pi 
. .'. • • , togel Lth I 

, in 

in pi • ■ ■ • 

••i theii 

it. 



- 3 



Dispersal and migratory flights occur during most of the adult 
period for both generations. For the first generation they take place 
when the air temperature is 80° F. or above,, whereas for the second 
generation some of the heaviest flights have taken place when the 
temperature was as low as 70°. 

Nymphs of the first generation will move into and all through an 
adjacent wheat field, but those of the second generation will remain 
close to the margin of wheat near the place where they hatched. For 
the first generation the nights are warm and the wheat is tall. For the 
second generation the nights are cool and the wheat is short, and the 
best protection from the cool nights is provided by the bordering tall 
weeds or sorghum plants. 

From the first time a second generation of mexicanus was recognized 
in western Kansas, it was recorded that both nymphs and adults were 
noticeably smaller than those of the first generation. In 1941 measure- 
ments of the pronotum, hind femur, and tegmina proved that all of them 
were significantly longer in the first generation than in the second. This 
was true again in 1951, when measurements of the second-generation 
adults proved them to be smaller than the first generation and also 
than some first-generation adults collected in Montana in 1927. 

In 1952 the second-generation nymphs and adults appeared to be as 
large as the first generation. Here again the same measurements were 
made of the second generation, but both males and females proved to 
be as large as the 1927 Montana and the first-generation 1941 Kansas 
specimens. No measurements were made of the adults of the first 
generation in Kansas in either 1951 or 1952. However, measurements 
of the fifth instars of the second generation in 1951 were smaller than 
those of either the first or second generations in 1952. There was 
little difference in size between these nymphs of the 1952 first and 
second generations at Tribune. 

Measurements of the adults and fifth-instar nymphs are given in 
table 1. In all three measurements of male and female adults the 
differences between the Kansas 1952 second generation and the Kansas 
1941 and 1951 second generations are highly significant but the differences 
between the second generation of 1952 and the first generation of Montana 
1927 and Kansas 1941 are not significant. The reasons for these differences 
are not known, but in the past largeness has been associated with the 
migratory, or outbreak, phase of mexicanus . Heavy flights of these 
large second-generation adults were observed in western Kansas on 
October 3, 1952, some of which in limited areas equaled in density 
the devastating swarms of 1938 and 1939. On one quarter section 
15 miles southwest of Tribune most of the volunteer wheat was de- 
stroyed by a swarm of these migrating adults. 



■ft 

■-■ 



. 



c 
c 



- 

* 

u Z 







— 








— « 


-. 


:: 






.. 


.- 


- 


— • 


— — • 




1 




>: 



c 




• 










— • 




• 






• 


B 












i 






• 

1 




1 




• 










V 











- 


1 

— 


Hind 
n u r 


- 


to 


. 


11. 
:ur 


3 


o 






• 
O 



o 



r; 



03 






PI 

r j 






- 



T) — — 





X 




~ 


























• 


• 


• 


• 


• 


• 


• 


• 






■"" ' 


— ' 











- 






■- 



- 

r 



t- 






- 



n 

















«-■ 
















• 







-- 



ITS 



CO 



X 



a> 


















— 


- 


t- 




r- 






• 


• 


• 


• 


• 


■ 








Tl 


1 


° 











X 




— 




3 






r- 


































—> 




C 








- 










• 


• 








































— 












-— 









« 




_« 
































- 5 - 



Fall Spraying to Protect Winter Wheat 

During the fall of 1951 in Stanton, Hamilton, and Greeley Counties, 
observations were made on the effectiveness of marginal spraying with 
aldrin to protect fall-seeded wheat from damage by second-generation 
mexicanus . Altogether 19 sections of farmland were included in these 
observations. All the spraying was done by plane at the rate of 3 ounces 
of aldrin in 1 gallon of fuel oil per acre. For each job 1 and sometimes 
2 strips, each 50 to 60 feet wide, of infested volunteer wheat or grain 
sorghum bordering the winter wheat were treated. At the time of 
spraying grasshopper damage was limited to the first 2 rods of wheat, 
and the plants themselves were either sprouted or had just passed the 
3-leaf stage of development. 

With the one application marginal infestations of 10 to 25 grass- 
hoppers per square yard were reduced to less than 1 per square yard, 
and damage was checked at once. The sorghum fields, many of which 
measured 0.3 mile wide by 1 mile long, had infestations averaging 3 to 
10 per square yard. The sprayed marginal strips remained low in 
infestation, less than 2 per square yard, for 9 to 19 days or until 
October 2. On that date a strong northwest wind, 25 to 30 miles per 
hour, blew new second-generation adults into the sprayed strips and 
adjacent wheat margins, increasing the infestations there to 6 to 8 
per square yard with a recurrence of some damage. These adults 
came from infestations within a half mile of the wheat margins. 

In two alfalfa fields, 80 and 40 acres, sprayed with aldrin August 30 
and September 1, respectively, the infestation remained at until 
October 2. After the wind, infestations averaged 2 to 3 per square 
yard and as high as 5 to 10 along the north margins of the fields. 

Some residual action of the insecticide was observed among those 
adults that were blown into strips that had been treated 19 days before. 
About 3 percent showed typical effects of the aldrin. In other places 
good residual action was observed up to 10 days after application. 

On one farm of 4 sections, 9 miles of wheat margins, or 64 acres, 
were sprayed twice with aldrin at 3 ounces per acre, on September 14 
and 29. All grasshopper infestations were eliminated. The cost was 
$80 for each application. 

In the general area most of the farmers were using poisoned bait 
to control their grasshoppers. Conclusions drawn from these observa- 
tions and from conversations with farmers were that those who figured 
control costs on the price of a sack of bait only, excluding any valuation 
of their own time, would go on using bait. Others who valued their time 
more than material costs and had the money to do it would go on spraying. 
The latter accepted the overall cost of the custom spray job as a part of 
their overhead even though spraying was more costly than baiting. 



K 

t the • 

K , tative 

there , l 

g. 

nade up 78 percent of tl. 
hatched nymphs v. i on April 28 and adults 

June 3 fig. 1 ). 

An in! - made of th< i on May 13 and 14 t< 

stations for spraying. Places so design.: - 

)Stly limited to fi< rgins m.: 

weedy fer ws and sectional graded and i 

re son id infestations that had developed from eggs hatching 

the wheat itself. Before the first spraying newly hatched nymphs had 
also moved 30 rods into the field from some margins. These infest 
tions numb* to 10 per squa' d and altogether \ -sted 

to 200 acres of wheat. 

1 he First Spray Operation 

The first s\ peration . nd end 

which time there no adults and 8' the nyi in 

the fourth, fifth, and sixth instars. Most s area 

ix instars in their d« rnent. Aldrin in an emulsion 

on 28 s of marj • :tions with a bl 

included 11. ies 

ties of a 8.5 i 

row, and 6.0 n, • I n in 

The ounces Ldrin . 

widths 

fie first 

■ 

■ 
the 

I 



- 7 - 



quarter-mile long, was it necessary to apply the spray a second time 
and then only because some mechanical difficulties reduced the dosage 
in the first application. 

At the time of the first spraying surveys were made of the farmland 
in the 15-mile-square district surrounding the spray area. Only three 
other places of limited size had infestations comparable to those on the 
spray area, and each involved two to four sections of farmland. Two of 
these were selected as check areas, one of two and the other of four 
sections (fig. 3). Early in the season the two-section area had infesta- 
tions of 100 to 150 grasshoppers per square yard in some of its margins, 
but there were only 10 to 50 per square yard in the four-section area. 
On two other areas, in Hamilton and Stanton Counties, both selected 
for the same purpose as the Tribune area, no infestations developed. 
The reason is discussed under "Cultivation as a Control Measure in 
Western Kansas," page 8. 

The Second Spray Operation 

On June 26 and 27 another intensive survey was made of the Tribune 
area. At this time the wheat harvest was within 10 days of completion. 
Most of the weedy margins treated early now contained 10 to 20 adult 
grasshoppers per square yard. Examinations of these places showed 
that enormous numbers of adults had been destroyed by the residual 
action of the aldrin as they moved back from the ripening and harvested 
wheat fields. This movement and action must have been continuous 
since the area was last visited on June 6. Proof of this lay in the fact 
that the dead adults were in all stages of decomposition and desiccation 
and that an occasional sick or recently dead grasshopper could be 
observed. Since there were no adults present when these margins were 
sprayed, those now found dead must have come from the fields. They 
numbered 10 to 200 per square yard in places, and in some depressions 
in the ground they were piled up in even greater numbers. 

Most of the residual action was gone by June 26, and it was deemed 
advisable to spray the margins again. On July 2, 250 acres of infested 
margins were sprayed by plane at the rate of 4 ounc es of aldrin in 1 
gallon of fuel oil per acre (see fig. 2). The spray strips were 3 rods 
wide. It took 1 hour and 20 minutes to do the job. It was done by a 
commercial operator hired by one of the farmers living in the area. 
The total cost for oil and application was $250, or $1 per acre. 
The Bureau furnished the aldrin. 

This second spraying reduced the infestations to 1 to 3 per square 
yard in the margins treated. On July 2 some dispersal flights were 
observed. The area was again visited on August 10, but there seemed 
to have been no reinfestation from the first-generation adults even 
though some dispersal flights were again observed. 






Fa 11 Sur v< 

I 

the si 
-ults of this su: 

■ 

numbered 8 • 
:. All the lighter I m argil 

adult , flight 

• 
This s 

tion, 
al flights o: id on 

similar flights of th» nd gei 

i e. They were ht 
t to 8 I . There is litl I ubt thai 

.dults over- t ht- entire spra; -11 as elsewher. 

to these dispersal flights. I >s many on the s{ I 

(fig. 4) as on the check area (: . Furthermore, the 

phs of th< >nd generation :ted that the 

second S] 4 had come < or 10 days too late to | t all egg 

deposition by the first generation. 

ised the worst d :e along the north 

t field in the SE 1/4 of se the SV 

. [). In bi '• h : Laces all the s] I • 

1 to 1 1/2 rods v 

show* .1 

• 
On th< io 

' ) 

I 
■ 
ed. Of 30 

■ 



- 9 - 



Most of these places were worked 1 to 3 times before and during the 
hatching period, and all the green food was destroyed by intense culti- 
vation to keep the weeds down. Previous observations recorded for 
similar conditions in northern Montana showed that newly hatched 
mexicanus nymphs had starved to death because green food was not 
within easy reach. The season in western Kansas was particularly 
favorable for early intensive cultivation, which is probably the reason 
why the general situation was one of light and spotted infestation during 
the first generation. 

It is therefore believed that these cultural practices are of great 
importance in the control of grasshoppers in this area. A large portion 
of the farming in western Kansas is being done by nonresident, or so- 
called "suitcase, " farmers, who are speculating and capitalizing on 
favorable economic and weather conditions. If these conditions change 
and large profits cannot be realized, many quarter sections of stubble 
will be left to grow up into weeds. Grasshoppers will promptly build 
up in these idle stubble fields. In the Dakotas in the thirties when one- 
third of the wheat was taken out of production, this species built up to 
the biggest outbreak of grasshoppers seen in modern times. The situa- 
tion in western Kansas bears watching 

Conclusions 

The dispersal flights of both generations of mexicanus in the vicinity 
of the Tribune spray area leveled off the infestations on and near the 
area and made it difficult to evaluate the good accomplished by the two 
sprayings of the first generation. The results of eliminating all infesta- 
tions on an area 20 sections in size can be neutralized by these flights. 

Nevertheless, this need not prevent making certain recommendations 
and expecting good results in emphasizing the control of the first genera- 
tion. It is important that the previous year's sorghum and wheat-stubble 
fields be thoroughly worked to reduce the problem to one of marginal 
infestation. Then aerial spraying of the field margins, including strips 
up to 30 rods wide into the wheat, when most of the first-generation 
nymphs are still concentrated along the edges, will eliminate most of 
the infestation. This application should be made the latter part of May, 
before adults appear. The residual action of this first application will 
eliminate large numbers of adults as they move into the sprayed margins 
from the ripening and harvested wheat. The recommended dosage for 
this early spraying is 2 ounces of aldrin per acre. If done with ground 
equipment, the coverage is uneven and as much as 2.5 ounces per acre 
may be used. Aerial spraying will permit wider marginal treatment 
and more uniform coverage, and an average dosage of 2 ounces of aldrin 
per acre is more likely to be obtained. 



10 



r s should be made la- :ne, 

: should < 
n. Tl I ted a 1 • 

A ■ • • • • ; . 

but this se :sest 

• 

In 1 ■ eas o: 

eratoi n be . at a r >st, but educatior. 

sivior. done. 



Digitized by the Internet Archive 

in 2013 



http://archive.org/details/spraoconOOunit 



11 - 





too 




90 




80 




70 


<M 




k. 


60 


3 




♦» 




C 


50 


i- 




0) 
Q. 


40 


E 




« 


30 


K 




■o 


20 


s 




o 


10 


■o 





o 

X 


o 




•♦- 


too 


o 




X 


90 


e 




o» 


to 


o 




+- 




c 


70 


« 




o 


60 


Q> 




a 


50 




40 




30 




20 




10 








1940 




J L_J I 



I I I 



II 21 5! 10 20 30 10 20 50 9 19 29 9 19 29 8 18 28 7 17 27 7 17 27 6 16 26 

March April May June July August Sept. October Nov. 



Figure 1. --Hatching periods of Melanoplus mexicanus, together with mean daily 
maximum temperatures, in Tribune, Kans., 1940 and 1952, and Havre, Mont., 
in 1940. Hatching period of first generation at Tribune (a) and Havre (b) and 
of second generation at Tribune (c). Mean daily maximum temperatures at 
Tribune (d) and Havre (e). 



- 12 



LEGEND 

0S«ction numbirj LIZ] Plowed f idda L ! Wh«ot f iddi i/nl* st <yfh«r ». <• )-- jnated 

iradodrojds - Section hne\ Hi'f jatfion Imet er •■! ♦-•-•-•- Roil rood 

" miNurnber* of qranhopper nymph* p€r ja. vd before $praymq floy 2t-3I 




W A>*Y* ^ < W »«<* /Art V» « »fr!iV*"i.,-. |r ll. l. l l i i.n J . ^,i,i-. i | ii i.n ,r riimn. r»|,r«r 

: 1 







i 



,..'..« 









: : 



m^wn w ?mitiv».':.i'..:/f; . 



■II 













■ 









V 






f: 



i . - I 



- 13 





A-Tu/y/ ; /<?52 



-►E 



A-Oot.-t 135 2 




Lis. 




B-Julyl,l<?5-2 



&-Oct<+,\°lSZ 



LEGEND 
©Section numbers. tBZb Plowed or seeded. I I Wheat stubble unless otherwise dcsianaisd HUH No. grasshoppers per sq-yd. 
= Graded roads. Section fines. half section lines or field margins, 'd'andnd' designate damaqeor nodamage 



Figure 3. --Two Tribune, Kans., check areas (A and B) when surveys were 
made of the first and second generations of Melanoplus rnexicanus. 



- 14 - 



II 



3 1262 09239 «224 



IQS3 winter- wh«at. -«at «fvbble unlets at 

■■' a/i roa d 



<nb«r* 
jded road* Section Unas Half auction linet or field marq -% 

grasshoppers per sq. yd as of Sep*. 27. 
d nd dctig^o^e damage or no damage by grasshoppe • - ^^^-^J^ 







' 



J, 



-f 









r-fr 









I 4— 






, a . ,,id J t _ 

■ 






i 



i 



X 



r 

-* 






( 



:. 






-, 



■ 



feu. 












^msm. 






i 
i 



r ... 



• . 



> • 



. ,...< 



- 



i 






•v 












1